Semiconductor devices and methods of making the same

ABSTRACT

In one embodiment, methods for making semiconductor devices are disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/834,612, filed Mar. 15, 2013, which is hereby incorporated byreference in its entirety.

BACKGROUND

The present application relates, in general, to electronics, and moreparticularly, to methods of forming packaging structure forsemiconductor devices.

The semiconductor industry typically utilizes various methods andstructures to form packages that encapsulate a semiconductor die andprovide leads for electrically connecting to the semiconductor die. Inone type of semiconductor package, the semiconductor die is mountedbetween a lead frame and a clip. The lower lead frame has a continuousflat surface on which the die is mounted then a clip is used to completethe electrical circuit on the top of the die. This configuration mayprovide inaccurate positioning of the semiconductor die to the lowerlead frame. In addition, the same inaccurate positioning can occur withthe clip. During mounting of both the die and clip, solder paste istypically used between the die to lead frame and clip to die. Duringreflow, both the die and clip may move, drift, tilt, and/or rotate,which can lower the quality and performance of the semiconductor device.

Accordingly, it is desirable to have techniques for mounting asemiconductor die that can reduce or eliminate drifting, tilting, orrotation. It is also desirable to have techniques for mounting differentsemiconductor dies using the same lead frame design.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of present application will become more fully understoodfrom the detailed description and the accompanying drawings, which arenot intended to limit the scope of the present application.

FIG. 1A is a perspective view illustrating one example of a lead framein accordance with some embodiments of the present application.

FIG. 1B is a top view one example of a lead frame in accordance withsome embodiments of the present application.

FIG. 1C is a cross-sectional view of source contact pad of a lead framein accordance with some embodiments of the present application.

FIGS. 2A and 2B are bottom and top views, respectively, illustrating oneexample of semiconductor die 200 in accordance with some embodiments ofthe present application.

FIG. 3A is a top view illustrating one example of semiconductor die 200positioned on lead frame 100 in accordance with some embodiments of thepresent application.

FIG. 3B is a cross-sectional view illustrating semiconductor die 200positioned on lead frame 100 in accordance with some embodiments of thepresent application.

FIG. 3C is a cross-sectional view illustrating semiconductor die 200positioned on lead frame 100 which is orthogonal to the cross-sectionalview in FIG. 3B in accordance with some embodiments of the presentapplication.

FIG. 4 is a perspective view illustrating one example of semiconductordevice 400 in accordance with some embodiments of the presentapplication.

FIG. 5A is a bottom view showing one example of universal conductiveclip 500 including a plurality of pedestals 510 that extend towardssemiconductor die 520 in accordance with some embodiments of the presentapplication.

FIG. 5B is a bottom view of one example of semiconductor die 521soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 5C is a bottom view of one example of semiconductor die 522soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 5D is a bottom view of one example of semiconductor die 523soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 5E is a bottom view of one example of semiconductor die 524soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 5F is a bottom view of one example of semiconductor die 525soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 5G is a bottom view of one example of semiconductor die 526soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 5H is a bottom view of one example of semiconductor die 527soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 5I is a bottom view of one example of semiconductor die 528soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 5J is a bottom view of one example of semiconductor die 529soldered to universal conductive clip 500 in accordance with someembodiments of the present application.

FIG. 6 shows examples of the design considerations when configuring auniversal conductive clip for family of semiconductor dies in accordancewith some embodiments of the present application.

For simplicity and clarity of the illustration, elements in the figuresare not necessarily to scale, and the same reference numbers indifferent figures denote the same elements. Additionally, descriptionsand details of well-known steps and elements are omitted for simplicityof the description. As used herein current carrying electrode means anelement of a device that carries current through the device such as asource or a drain of an MOS transistor or an emitter or a collector of abipolar transistor or a cathode or anode of a diode, and a controlelectrode means an element of the device that controls current throughthe device such as a gate of an MOS transistor or a base of a bipolartransistor. Although the devices are explained herein as certainN-channel or P-Channel devices, or certain N-type of P-type dopedregions, a person of ordinary skill in the art will appreciate thatcomplementary devices are also possible in accordance with the presentinvention. It will be appreciated by those skilled in the art that thewords during, while, and when as used herein are not exact terms thatmean an action takes place instantly upon an initiating action but thatthere may be some small but reasonable delay, such as a propagationdelay, between the reaction that is initiated by the initial action. Theuse of the word approximately or substantially means that a value ofelement has a parameter that is expected to be very close to a statedvalue or position. However, as is well known in the art there are alwaysminor variances that prevent the values or positions from being exactlyas stated. It is well established in the art that variances of up toabout ten percent (10%) (and up to twenty percent (20%) forsemiconductor doping concentrations) are regarded as reasonablevariances from the ideal goal of exactly as described. For clarity ofthe drawings, doped regions of device structures are illustrated ashaving generally straight line edges and precise angular corners.However, those skilled in the art understand that due to the diffusionand activation of dopants the edges of doped regions generally may notbe straight lines and the corners may not be precise angles.

DETAILED DESCRIPTION

The following description of embodiment(s) is merely illustrative innature and is in no way intended to limit the invention, itsapplication, or uses. The present application includes, among otherthings, a method of making a semiconductor device including: providing aconductive substrate, the conductive substrate comprising one or moreelevated regions on a first side of the conductive substrate, whereineach of the elevated regions comprises a planar surface on the firstside of the conductive substrate; disposing a solder paste between atleast one of the planar surfaces on the elevated regions on theconductive substrate and one or more contact pads of a semiconductor diesuch that each of the contacts pads has three or more linear edges thatare each laterally aligned and parallel with at least one edge of theplanar surfaces on the elevated regions; and reflowing the solder pasteto solder at least a portion of the elevated regions to the contactpads.

FIG. 1A is a perspective view illustrating one example of lead frame 100in accordance with some embodiments of the present application. Leadframe 100 includes source contact 110, gate contact 120, and draincontact 130. Source contact 110 includes pedestals 140 (also referred toas standoffs or elevated regions) disposed on one side of source contact110. Lead frame 100 may be formed, for example, by etching or stamping acopper or copper-alloy sheet. FIG. 1B is a top view of lead frame 100.It will be appreciated that during typical packaging processes, the leadframe and its various contacts (e.g., source contact 110) may beinterconnected in an array of lead frames that can be singulated intoindividual packages during processing. The dashed line in FIG. 1Bdepicts cuttings lines where lead frame 100 can be separated usingstandard techniques, such as dicing or punching. FIG. 1C is across-sectional view of source contact pad 110 in lead frame 100.Pedestals 140 can be isolated by trenches 150 between pedestals 140.Pedestals 140 each have planar surfaces on the same side of lead frame100. As discussed further below, the pedestals can be configured toalign with contact pads on a semiconductor die.

The height of the pedestals (e.g., pedestals 140) can be, in someembodiments, at least about 30% of a thickness of the contact. Forexample, the source contact may be formed from a copper sheet having athickness of about 10 mils, and therefore the height of the pedestalscan be at least about 3 mils. In some embodiments, the pedestals canhave a height of at least about 50% of a thickness of the contact. Insome embodiments, the pedestals can, in some embodiments, have a heightof at least about 3 mils or at least about 5 mils. The distance betweenthe pedestals (e.g., the width of trenches 150) can be, in someembodiments, at least about the height of the pedestals. In someembodiments, the distance between the pedestals can be at least about30% of a thickness of the contact or at least about 50% of a thicknessof the contact. The distance between the pedestals can be, for example,at least about 3 mils or at least about 5 mils.

The shape of the pedestals is not particularly limited. The top surfaceof the pedestals may, for example, have a polygonal surface, such as asquare, a rectangle, or a triangle. In some embodiments, the top surfaceof each of the pedestals can include at least one linear edge (e.g.,one, two, three, four or more linear edges). For example, as shown inFIG. 1B pedestals 140 can be rectangular having four linear edges. Thepedestals may also include at least one curved edge, for example, toaccommodate an adjacent gate contact.

FIGS. 2A and 2B are bottom and top views, respectively, illustrating oneexample of semiconductor die 200 in accordance with some embodiments ofthe present application. Semiconductor die 200 includes source contactpads 210 and gate contact pad 220 on one side. Semiconductor die 200also includes drain contact pad 230 on a side of semiconductor die 200opposite source contact pads 210. Semiconductor die 200 may beconfigured, for example, as a MOSFET. Source contact pads 210 can beconfigured so that each of the contact pads can be soldered to apedestal on a source contact of a lead frame (e.g., pedestals 140 onsource contact 110 of lead frame 100). For example, each of sourcecontact pads 210 may have the same shape and dimensions as acorresponding pedestal in pedestals 140 on source contact 110.Semiconductor die 200 may have the bottom surface placed over lead frame100 such that each of source contact pads 210 align with one ofpedestals 140. Similarly, gate contact pad 210 on semiconductor die 200may align with gate contact 120 of lead frame 100.

FIG. 3A shows a top view illustrating one example of semiconductor die200 positioned on lead frame 100 in accordance with some embodiments ofthe present application. Semiconductor die 200 is shown with dashedlines and is positioned over lead frame 100 so that source contact pads210 can be aligned over pedestals 140. Each of the pedestals frompedestals 140 include four linear edges that are laterally aligned andparallel with four linear edges of each contact pad in contact pads 210.(The right-most pedestal of pedestals 140 also includes a curved edgethat is laterally aligned with a curved edge of the right-most sourcecontact pad of source contact pads 210.) Gate contact pad 220 is alsoaligned over gate contact 120. The pedestals can be soldered to thesource contact pads to electrically couple source contact 110 to sourcecontact pads 220.

FIG. 3B show a cross-sectional view illustrating semiconductor die 200positioned on lead frame 100 in accordance with some embodiments of thepresent application. Solder paste 300 can be disposed between each ofcontact source pads 220 and pedestals 140. The solder paste may beapplied such that trenches 150 are substantially free of solder paste.For example, solder paste 300 can be selectively applied to pedestals140 before positioning semiconductor die 200 on lead frame 100 so thatsolder paste 300 is sandwiched between source contact pads 210 andpedestals 140. Solder paste may similarly be disposed between gatecontact pad 220 and gate contact 120.

The amount of solder paste applied between the pedestals and the contactpads is not particularly limited. Generally, the amount of solder pasteapplied is effective to electrically couple the contact pad to theconductive surface (e.g., the lead frame) and also effective such thatthe solder paste does not bridge between the pedestals during reflow. Insome embodiments, the solder paste is evenly applied as a layer to theportions of the pedestal or contact pad to be soldered during reflow. Insome embodiments, the solder paste is applied as a layer having athickness about 0.003 inches to about 0.006 inches.

Pedestals 140 can be soldered to source contact pads 210 by heating thesemiconductor die and lead frame to perform reflow. In some embodiments,during reflow, the solder paste is maintained between the pedestals andthe contact pads. That is, the solder paste does not flow into thetrenches surrounding the pedestals. Similarly, the separate layers ofsolder paste disposed between each pair of contact pad and pedestal canremain spaced apart during reflow. In other words, layers of solderpaste do not flow into a trench adjacent to both of the layers such thatthe solder paste from separate layers contact each other.

Applicants have discovered that by soldering the pedestals to thecontact pads, drifting, tilting, or rotation during reflow can bereduced or eliminated. Without being bound to any particular theory, itis believed that, by aligning edges of the pedestals with edges of thecontact pads, the solder's surface tension and wet adhesion propertiesduring reflow can maintain the pedestals aligned with the contact pads.This in turn limits or prevents the semiconductor die from rotating,tilting, or drifting during reflow.

Accordingly, in some embodiments, each contact pad that is soldered to apedestal will have two or more linear edges that are each laterallyaligned and parallel with a linear of edge of a pedestal that issoldered to the contact pad. In some embodiments, each contact pad thatis soldered to a pedestal will have three or more linear edges that areeach laterally aligned and parallel with a linear of edge of a pedestalthat is soldered to the contact pad. In some embodiments, each contactpad that is soldered to a pedestal will have four or more linear edgesthat are each laterally aligned and parallel with a linear of edge of apedestal that is soldered to the contact pad. In some embodiments, eachcontact pad that is soldered to a pedestal will have two or more cornersthat are each laterally aligned with a corner of a pedestal that issoldered to the contact pad. In some embodiments, each contact pad thatis soldered to a pedestal will have three or more corners that are eachlaterally aligned with a corner of a pedestal that is soldered to thecontact pad. In some embodiments, each contact pad that is soldered to apedestal will have four or more corners that are each laterally alignedwith a corner of a pedestal that is soldered to the contact pad.

As will be discussed further below, a single contact pad may optionallybe soldered to two or more pedestals (e.g., two, three, four, five, six,or more pedestals). Thus, different linear edges of the same contact padcan be laterally aligned and parallel to edges of different pedestals.As an example, a rectangular contact pad can be soldered to two squarepedestals. The rectangular contact pad may have two linear edges thatare laterally aligned and parallel with two linear edges of the firstsquare pedestal. The other two linear edges of the rectangular contactpad can be laterally aligned and parallel with two linear edges of thesecond square pedestal. Thus, in this specific example, all four linearedges of the rectangular contact pad are laterally aligned and parallelwith linear edges found in two different pedestals. Moreover, each ofthe square pedestals includes two linear edges that are not laterallyaligned with a linear edge of the rectangular contact pad. This exampleconfiguration may provide suitable adhesion to prevent drifting,tilting, or rotation during reflow. In some embodiments, at least twocontact pads are each separately soldered to two or more pedestals. Forexample, a first contact pad (e.g., a source contact pad) of asemiconductor die can be soldered to a first pedestal of a contact(e.g., a source contact) on a lead frame and a second pedestal of thecontact on the lead frame, and a second contact pad of the semiconductordie can be soldered to a third pedestal of the contact on the lead frameand a fourth pedestal of the contact on the lead frame.

Drain contact pad 230 on semiconductor die 200 may be electricallycoupled to drain contacts 130 on lead frame 100 using varioustechniques. For example, drain contact pad 230 can be wire bonded todrain contacts 130. In some embodiments, drain contact pad 230 can beelectrically coupled to drain contacts 130 by a conductive clip. Theconductive clip may be soldered to both drain contact pad 230 and draincontacts 130. FIG. 3C is a cross-sectional view illustratingsemiconductor die 200 positioned between lead frame 100 and conductiveclip 310. The cross-sectional view in FIG. 3C is orthogonal to thecross-sectional view in FIG. 3B. The bottom face of conductive clip 310can be soldered to drain contact pad 230 using solder paste 320.Conductive clip 310 has a U-shaped configuration such that both ends canbe soldered to drain contacts 130 in lead frame 100 using solder paste330. By soldering conductive clip 310 to both drain contacts 130 anddrain contact pad 230, drain contact 130 can be electrically coupled todrain contact pad 230. As shown in FIG. 3C, gate contact 120 can besoldered to gate contact pad 210 using solder paste 340. Gate contact120 may be soldered to gate contact pad 210 at about the same time asperforming reflow to solder source contact pad 220 to source contact110.

The conductive clip can be soldered to the contact pad (e.g., a gatecontact pad) and contact on the lead frame (e.g., a gate contact) usinggenerally the same techniques as described above. For example, solderpaste can be applied to the gate contact pad and gate contacts, and thenthe conductive clip can positioned to contact the solder paste beforeperforming reflow. The reflow for soldering the conductive clip may beperformed before, after, or at about the same time as performing reflowto solder the semiconductor die to the lead frame.

As discussed above, the pedestals on the lead frame can reduce orprevent drifting, tilting, or rotation during reflow. The pedestals mayalso be used to prevent or reduce drifting, tilting, or rotation whensoldering any conductive substrate (e.g., a conductive clip or a leadframe) to a contact pad on a semiconductore die.

FIG. 4 is a perspective view illustrating one example of semiconductordevice 400 in accordance with some embodiments of the presentapplication. Semiconductor device 400 can include source contact 410soldered to conductive clip 420. Conductive clip 420 has pedestals 425which extend from the side of conductive clip 420 that facessemiconductor die 430. Pedestals 425 can be soldered to source contactpads 435 on semiconductor die 430 such that source contact 410 iselectrically coupled to source contact pads 435. As shown, four linearedges of the contact pads that are soldered to the pedestals are eachlaterally aligned and parallel with a linear of edge of a pedestal thatis soldered to the contact pad. The pedestals on the conductive clip maytherefore reduce or prevent drifting, tilting, or rotation duringreflow. Drain contact 440 can be soldered to drain contact pads (notshown) on a side of semiconductor die 430 opposite source contact pads435. Gate contact 450 is soldered to conductive clip 460. Gate contactpad 470 on semiconductor die 430 is also soldered to conductive clip 460such that gate contact 470 is electrically coupled to gate contact pad470.

The pedestals on a conductive substrate (e.g., pedestals 425 onconductive clip 420) can generally have the same characteristics asdiscussed above with regard to pedestals on a lead frame (e.g.,pedestals 140 on lead frame 100). For example, the height of thepedestals may be about half of the thickness of the conductive clip. Asanother example, the number of pedestals on the conductive substrate isnot limited, and may be, for example, one or more pedestals (e.g., one,two, three, four, five, ten, fifteen, twenty, or more pedestals on theconductive substrate). In some embodiments, at least one contact pad(e.g., one, two, three, four, or more contact pads) on the semiconductordie is soldered to two or more pedestals (e.g., two, three, four, five,or more pedestals) on the conductive substrate.

Semiconductor device 400 may generally be assembled using the sametechniques as described above. Solder paste can be applied to the draincontact and then the drain contact is soldered to the drain contact padon the semiconductor die by performing reflow. Solder paste may then beapplied to the source contact pad, gate contact pad, source contact, andgate contact before positioning the conductive clips over thesemiconductor die and lead frame. Reflow can be performed to solder theconductive clip. In some embodiments, the semiconductor die's contactpads are soldered to the lead frame and conductive clips at about thesame time.

The semiconductor devices disclosed in the present application (e.g.,semiconductor device 400) may be at least partially encapsulated in amolding material (e.g., a resin). In some embodiments, the moldingmaterial can fill the trenches between the pedestals. Portions of thelead frame and/or conductive clip may be exposed for electricallycoupling the semiconductor die to, for example, a printed circuit board.

Some embodiments disclosed herein relate to a conductive substrate thatis configured to operably couple with two or more differentsemiconductor die designs (e.g., two, three, four, five, or moresemiconductor die designs). Typically, each lead frame or conductiveclip is customized for soldering to a specific semiconductor die design.Thus, each semiconductor die design requires a different lead framedesign that must be manufactured or stocked at manufacturing facilities.The present application includes a universal lead frame and/or universalconductive clip that may be used with various kinds of semiconductor diedesigns. This may reduce the number of different lead fames that must bemanufactured or stocked at manufacturing facilities.

FIGS. 5A-J are bottom views illustrating one example of universalconductive clip 500 soldered to various semiconductor dies in accordancewith some embodiments of the present application. Referring to FIG. 5A,universal conductive clip 500 includes a plurality of pedestals 510 thatextend towards semiconductor die 520. Semiconductor die 520 has contactpads 530 on one side that are each soldered to two or more pedestals ofpedestals 510. The upper-left contact pad is soldered to two pedestals.The upper-left contact pad has two linear edges that are each laterallyaligned and parallel with an edge on the upper-left pedestal that issoldered to the upper-left contact pad. The upper-left contact pad andupper-left pedestal each have curved edges that are laterally aligned.The curved edges are shaped to accommodate contact pad 540 which can beelectrically coupled to a separate conductive clip (not shown). Theupper-left contact pad is also soldered to a second pedestal below theupper-left pedestal. Only a portion of the top surface of the secondpedestal is soldered to the upper-left contact pad. Two edges of thesecond pedestal are each laterally aligned and parallel with an edge ofthe upper-left contact pad. During manufacturing, solder paste can beselectively applied to the top surface of the second pedestal (and anyother pedestal having only a portion of the top surface soldered to acontact pad) at portions that will contact a contact pad.

Each of contact pads 530 in FIG. 5A have two or more edges that are eachlaterally aligned and parallel with an edge of a pedestal. The number ofpedestals soldered to each contact pad varies: the upper-left andlower-left contact pads are each soldered to two pedestals, theupper-right and lower-right contact pads are each soldered to fourpedestals. Each of the contact pads has only a portion of their surfacearea soldered to the pedestals. The portions of the contact padsdisposed over trenches between the pedestal can, in some embodiments, beunsoldered. The total surface area of each contact pad that is solderedto a pedestal can be, for example, at least about 40%, at least about50%, at least about 75%, or at least about 90%. The total surface areaof each contact pad that is soldered to a pedestal can be, for example,no more than about 100%, no more than about 95%, no more than about 90%,no more than about 80%, or no more than about 70%. In some embodiments,the total surface area of each contact pad that is soldered to apedestal is about 40% to about 100%, or about 50% to about 95%.

Eight of the pedestals in pedestals 510 depicted in FIG. 5A are notsoldered to a contact pad. As will be discussed further below, theseunsoldered pedestals are designed for a different semiconductor die.Four of the pedestals are laterally positioned away from the footprintof semiconductor die 520. In other words, four of the pedestals are notcovered by semiconductor die 520. Another four of the pedestals are onlypartially covered by semiconductor die 520.

FIG. 5B shows semiconductor die 521 soldered to universal conductiveclip 500. Semiconductor die 521 has a different footprint and contactpad configuration relative to semiconductor die 520. However, contactpad 540 (e.g., a gate contact pad) has the same configuration in bothsemiconductor dies. Each of contact pads 531 are soldered to fourpedestals of pedestals 510. As shown, each of contact pads 531 have fouredges that are each laterally aligned and parallel with edges on thepedestals soldered to the contact pads. Each of the eight pedestals thatare soldered have their entire top surface soldered to the contact pads.Twelve pedestals remain unsoldered to semiconductor die 531: ten areuncovered by the footprint of semiconductor die 531, while two arepartially covered by the footprint of semiconductor die 531.

FIG. 5C shows semiconductor die 522 soldered to universal conductiveclip 500. Semiconductor die 522 has a different footprint and contactpad configuration. However, contact pad 540 (e.g., a gate contact pad)has the same configuration relative to semiconductor die 520. The leftcontact pad of contact pads 532 is soldered to two pedestals ofpedestals 510. The right contact pad of contact pads 532 is soldered tofour pedestals of pedestals 510. The pedestals soldered to the leftcontact pad have their entire top surface soldered to the left contactpad. Two of the pedestals soldered to the right contact pad have only aportion of their top surface soldered to the right contact pad. Two ofthe pedestals soldered to the right contact pad have their entire topsurface soldered to the right contact pad. Fourteen pedestals remainunsoldered to semiconductor die 522: twelve are uncovered by thefootprint of semiconductor die 522, while two are partially covered bythe footprint of semiconductor die 522.

FIG. 5D shows semiconductor die 523 soldered to universal conductiveclip 500. Semiconductor die 523 has a different footprint and contactpad configuration. However, contact pad 540 (e.g., a gate contact pad)has the same configuration relative to semiconductor die 520. Theleft-most contact pad of contact pads 533 is soldered to six pedestalsof pedestals 510. The pedestals soldered to the left-most contact padhave their entire top surface soldered to the left-most contact pad. Theright-most contact pad of contact pads 533 is soldered to four pedestalsof pedestals 510. Two of the pedestals soldered to the right-mostcontact pad have their entire top surface soldered to the right-mostcontact pad. Two of the pedestals soldered to the right-most contact padhave only a portion of their top surface soldered to the right-mostcontact pad. Fourteen pedestals remain unsoldered to semiconductor die523: twelve are uncovered by the footprint of semiconductor die 523,while two are partially covered by the footprint of semiconductor die523.

FIG. 5E shows semiconductor die 524 soldered to universal conductiveclip 500. Semiconductor die 524 has a different footprint and contactpad configuration. However, contact pad 540 (e.g., a gate contact pad)has the same configuration relative to semiconductor die 520.Semiconductor die 524 has two contact pads in contact pads 534 which areeach soldered to four pedestals.

FIG. 5F shows semiconductor die 525 soldered to universal conductiveclip 500. Semiconductor die 525 has a different footprint and contactpad configuration. However, contact pad 540 (e.g., a gate contact pad)has the same configuration relative to semiconductor die 520.Semiconductor die 525 has three contact pads in contact pads 534. Alltwenty of pedestals 510 are soldered to contact pads 535. In someembodiments, semiconductor die 535 may be the largest semiconductor diethat can be accommodated on universal conductive clip 500.

FIG. 5G shows semiconductor die 526 soldered to universal conductiveclip 500. Semiconductor die 526 has a different footprint and contactpad configuration. However, contact pad 540 (e.g., a gate contact pad)has the same configuration relative to semiconductor die 520.Semiconductor die 526 has two contact pads in contact pads 536 which areeach soldered to two pedestals.

FIG. 5H shows semiconductor die 527 soldered to universal conductiveclip 500. Semiconductor die 527 has a different footprint and contactpad configuration. However, contact pad 540 (e.g., a gate contact pad)has the same configuration relative to semiconductor die 520.Semiconductor die 527 has contact pad 537 which is soldered to threepedestals.

FIG. 5I shows semiconductor die 528 soldered to universal conductiveclip 500. Semiconductor die 528 has a different footprint and contactpad configuration. However, contact pad 540 (e.g., a gate contact pad)has the same configuration relative to semiconductor die 520.Semiconductor die 528 has two contact pads in contact pads 538: aleft-most contact pad soldered to six pedestals and a right-most contactpad soldered to nine pedestals. The left-most and right-most contactpads are both soldered to three common pedestals positioned between thecontact pads. The portions of the common pedestals between the contactpads are not soldered. For example, solder paste may be selectivelyapplied to only portions of the top surfaces of the common pedestalsthat contact the contact pads. The portions having soldering pastapplied can then be soldered by performing reflow.

FIG. 5J shows semiconductor die 529 soldered to universal conductiveclip 500. Semiconductor die 529 has a different footprint and contactpad configuration. However, contact pad 540 (e.g., a gate contact pad)has the same configuration relative to semiconductor die 520.Semiconductor die 529 has three contact pads in contact pads 539. Theleft-most contact pad is soldered to three pedestals, the middle contactpad is soldered to six pedestals, and the right-most contact pad issoldered to six pedestals.

The configuration of the conductive clip will vary depending on thefamily of semiconductor dies that are desired to be attached. The size,shape, and spacing of the pedestals can be readily modified toaccommodate a family of different semiconductors. In some embodiments,the universal conductive clip can be configured to align certain cornerson the contact pads in each semiconductor die in the family. Forexample, the corners on the contact pads closest to a corner of thesemiconductor die may be laterally aligned with corners on thepedestals. In some embodiments, two, three, or four of the closestcorners are laterally aligned with the pedestals. Similarly, edges ofthe contact pads that form a corner closest to a corner of thesemiconductor die can be laterally aligned and parallel with an edge ofa pedestal. In some embodiments, two, three, or four pairs of linearedges of the contact pads that form a corner closest to a corner of thesemiconductor die can be laterally aligned and parallel with an edge ofa pedestal. FIGS. 5A-J each demonstrate a configuration where fourcorners of the contacts pads closest to the corners of the semiconductordie are laterally aligned. FIGS. 5A-J each demonstrate having threepairs of linear edges of the contact pads that form a corner closest toa corner of the semiconductor die that are laterally aligned andparallel with an edge of a pedestal (the corners closest to contact pad540 are not formed by two linear edges).

FIG. 6 shows examples of the design consideration when configuring auniversal conductive clip in accordance with some embodiments of thepresent application. Conductive clip 600 can have first pedestal 605,second pedestal 610, third pedestal 615, and fourth pedestal 620 at theouter corners of the array of pedestals. The positioning at outercorners can be selected to accommodate the largest contact pad footprintin the semiconductor die family. The pedestals at the outer corners maybe configured so that the outer edges are laterally aligned and parallelwith contact pads (e.g., as depicted in FIG. 5F the outer cornerpedestals on conductive clip 500 are soldered to contact pads 535 onsemiconductor die 525 so that the outer edges are laterally aligned andparallel).

Width 625 of the left-most column of pedestals (including first pedestal605 and fourth pedestal 620) can be based on the smallest width of acontact pad in the family. For example, the width of the left-mostcolumn of pedestals in universal conductive clip 500 corresponds to thewidth of the left-most contact pads in semiconductor die 535 andsemiconductor die 539. Height 630 of the upper-most row of pedestals canbe based on the smallest height of a contact pad in the family. Forexample, the height of the upper-most row of pedestals in universalconductive clip 500 corresponds to the height of contact pads 536 andcontact pads 537 in semiconductor die 536 and semiconductor die 537,respectively. Pitch 635 and height 640 can be determined by analyzingthe intermediate-sized semiconductor dies in the family (e.g.,semiconductor die 523 and the like for conductive clip 500 as depictedin FIGS. 5A-J)

The universal design for the universal conductive clip described abovemay similarly be applied to other conductive substrates, such as a leadframe. Thus, some embodiments disclosed herein include a universal leadframe having two or more pedestals that can accommodate different-sizedsemiconductor dies. The universal lead frame may generally have the samecharacteristics as the universal conductive clip described above (e.g.,universal conductive clip 500 as depicted in FIGS. 5A-J). In someembodiments, a semiconductor die can be soldered to the lead frame suchthat at least a portion of the pedestals are not soldered to a contactpad. In some embodiments, a semiconductor die can be soldered to thelead frame such that at least a portion of the unsoldered pedestals arenot covered by the footprint of the semiconductor die.

Some embodiments disclosed herein include a kit for manufacturingsemiconductor devices. The kit can include two or more differentsemiconductor dies having different contact pad configurations. The kitcan include a universal conductive substrate (e.g., a universal leadframe or a universal conductive clip) that is configured to be solderedto the semiconductor dies. The universal conductive substrate caninclude pedestals configured so that each of the semiconductor dies canhave contact pads operably coupled to the pedestals. As an example, thekit can include conductive clip 500 and semiconductor dies 520-529 asdepicted in FIGS. 5A-J. In some embodiments, the pedestals on theuniversal conductive substrate are configured so that two, three, orfour of the closest corners on the contact pads (the corners on thecontacts pads closest to the corners on the semiconductor die) for eachof the semiconductor dies are laterally aligned with the pedestals. Insome embodiments, two, three, or four pairs of linear edges of thecontact pads that form the closest corners for each of the semiconductordies can be laterally aligned and parallel with an edge pair of apedestal.

Some embodiments disclosed herein include a method of making asemiconductor die. The method may be used, for example, to prepare anyof the semiconductor devices disclosed in the present application (e.g.,semiconductor device 400 as depicted in FIG. 4). The method can includeproviding a conductive substrate (e.g., lead frame 100 as depicted inFIG. 1A). The conductive substrate can include one or more pedestals ona first side of the conductive substrate, wherein each of the pedestalscomprises a planar surface on the first side of the conductive substrate(e.g., pedestals 140 as depicted in FIG. 1A). The method may alsoinclude disposing a solder paste between at least one of the planarsurfaces on the pedestals on the conductive substrate and one or morecontact pads of a semiconductor die such that each of the contacts padshas two or more linear edges that are each laterally aligned andparallel with at least one edge of the planar surfaces on the pedestals(e.g., solder paste 300 and soldering past 340 are applied as depictedin FIGS. 3B-C). The method can also include reflowing the solder pasteto solder at least a portion of the pedestals to the contact pads.

From all the foregoing one skilled in the art can determine thataccording to one embodiment, a semiconductor device comprises: a leadframe comprising a first contact electrically coupled to a first lead,wherein the first contact comprises one or more elevated regions on afirst side of the first contact, wherein each of the elevated regionscomprises a planar surface on the first side of the first contact; asemiconductor die comprising one or more first contact pads, a secondcontact pad, and a third contact pad, wherein the first contact pads aredisposed on a first side of the semiconductor die, and wherein each ofthe first contact pads are soldered to at least one of the elevatedregions such that each of the first contacts pads has two or more linearedges that are each laterally aligned and parallel with at least oneedge of the planar surfaces on the elevated regions; a second leadelectrically coupled to the second contact pad of the semiconductor die;and a third lead electrically coupled to the third contact pad of thesemiconductor die.

From all the foregoing one skilled in the art can determine thataccording to one embodiment, a semiconductor device comprises: a leadframe comprising a first contact electrically coupled to a first lead ofthe semiconductor device; a conductive clip electrically coupled to asecond lead on the semiconductor device, wherein the conductive clipcomprises one or more elevated regions on a first side of the conductiveclip, wherein each of the elevated regions comprises a planar surface onthe first side of the conductive clip; and a semiconductor diecomprising: a first contact pad on a first side of the semiconductordie, wherein the first contact pad is soldered to the first contact onthe lead frame; one or more second contact pads on a second a side ofthe semiconductor die, wherein each of the second contact pads aresoldered to at least one of the elevated regions on the first side ofthe conductive clip such that each of the second contacts pads has twoor more linear edges that are each laterally aligned and parallel withat least one edge of the planar surfaces on the elevated regions; and athird contact pad on the semiconductor die, wherein the third contactpad is electrically coupled to a third lead of the semiconductor device.

From all the foregoing one skilled in the art can determine thataccording to one embodiment, a method of making a semiconductor devicecomprises: providing a conductive substrate, the conductive substratecomprising one or more elevated regions on a first side of theconductive substrate, wherein each of the elevated regions comprises aplanar surface on the first side of the conductive substrate; disposinga solder paste between at least one of the planar surfaces on theelevated regions on the conductive substrate and one or more contactpads of a semiconductor die such that each of the contacts pads has twoor more linear edges that are each laterally aligned and parallel withat least one edge of the planar surfaces on the elevated regions; andreflowing the solder paste to solder at least a portion of the elevatedregions to the contact pads.

In view of all of the above, it is evident that a novel device andmethod is disclosed. Included, among other features, are conductivesubstrates, such as a lead frame or conductive clip, having elevatedregions that can reduce or prevent drifting, tilting, or rotation duringreflow. Furthermore, universal conductive substrates configured to beoperably soldered to different semiconductor dies are disclosed.

While the subject matter of the invention is described with specificpreferred embodiments and example embodiments, the foregoing drawingsand descriptions thereof depict only typical embodiments of the subjectmatter and are not therefore to be considered to be limiting of itsscope, it is evident that many alternatives and variations will beapparent to those skilled in the art. For example, the subject matterhas been described with respect to particular transistor configurationsfor the semiconductor die, however various different integrated circuitsmay also be used. As another example, the subject matter has beendescribed with respect to soldering contact pads to conductivesubstrates, however other techniques for electrically coupling thecontact pads to the conductive substrate may also be used.

As the claims hereinafter reflect, inventive aspects may lie in lessthan all features of a single foregoing disclosed embodiment. Thus, thehereinafter expressed claims are hereby expressly incorporated into thisDetailed Description, with each claim standing on its own as a separateembodiment of an invention. Furthermore, while some embodimentsdescribed herein include some but not other features included in otherembodiments, combinations of features of different embodiments are meantto be within the scope of the invention, and form different embodiments,as would be understood by those skilled in the art.

What is claimed is:
 1. A semiconductor device comprising: a conductivesubstrate electrically coupled to a first lead, wherein the conductivesubstrate comprises a first elevated region on a first side of theconductive substrate and second elevated region on the first side of theconductive substrate, wherein the first elevated region comprises afirst planar surface on the first side of the conductive substrate, andwherein the second elevated region comprises a second planar surface onthe first side of the conductive substrate; and a semiconductor diecomprising a first contact pad electrically coupled to the conductivesubstrate, wherein the first contact pad is soldered to both the firstplanar surface of the first elevated region and the second planarsurface of the second elevated region, and wherein the first planarsurface of the first elevated region has different dimensions than thesecond planar surface of the second elevated region.
 2. Thesemiconductor device of claim 1, wherein the conductive substratecomprises at least 10 elevated regions.
 3. The semiconductor device ofclaim 2, wherein a number of the elevated regions on the first side ofthe conductive substrate is greater than a number of the elevatedregions on the first side of the conductive substrate soldered to thesemiconductor die.
 4. The semiconductor device of claim 1, wherein theconductive substrate and the semiconductor die are at least partiallyencapsulated in a molding material.
 5. The semiconductor device of claim4, wherein the molding material is disposed between the first elevatedregion and the second elevated region.
 6. The semiconductor device ofclaim 1, wherein the first planar surface of the first elevated regionhas a first corner that is laterally aligned with a first corner of thefirst contact pad.
 7. The semiconductor device of claim 6, wherein thesecond planar surface of the second elevated region has a second cornerthat is laterally aligned with a second corner of the first contact pad.8. The semiconductor device of claim 6, wherein the first planar surfaceof the first elevated region has a second corner that is laterallyaligned with a second corner of the first contact pad.
 9. Thesemiconductor device of claim 1, wherein the conductive substratefurther comprises a third elevated region on the first side of theconductive substrate, wherein the third elevated comprises a thirdplanar surface on the first side of the conductive substrate, andwherein the first contact pad is soldered to the third planar surface ofthe third elevated region.
 10. The semiconductor device of claim 9,wherein the first planar surface of the first elevated region has afirst corner that is laterally aligned with a first corner of the firstcontact pad, wherein the second planar surface of the second elevatedregion has a second corner that is laterally aligned with a secondcorner of the first contact pad, and wherein the third planar surface ofthe third elevated region has a third corner that is laterally alignedwith a third corner of the first contact pad.
 11. The semiconductordevice of claim 1, wherein only a portion of the first planar surface ofthe first elevated region is soldered to the first contact pad.
 12. Asemiconductor device comprising: a conductive substrate electricallycoupled to a first lead, wherein the conductive substrate comprises afirst elevated region on a first side of the conductive substrate, asecond elevated region on the first side of the conductive substrate,and a third elevated region on the first side of the conductivesubstrate, wherein the first elevated region comprises a first planarsurface on the first side of the conductive substrate, wherein thesecond elevated region comprises a second planar surface on the firstside of the conductive substrate, and wherein the third elevated regioncomprises a third planar surface on the first side of the conductivesubstrate; and a semiconductor die comprising a first contact pad and asecond contact pad electrically coupled to the conductive substrate,wherein the first contact pad is soldered to the first planar surface ofthe first elevated region and the second contact pad is soldered to thesecond planar surface of the second elevated region, and wherein thethird planar surface of the third elevated region is not soldered to thesemiconductor die.
 13. The semiconductor device of claim 12, wherein thethird planar surface of the third elevated region is laterallypositioned away from a footprint of the semiconductor die.
 14. Thesemiconductor device of claim 13, wherein the conductive substratefurther comprises a fourth elevated region on the first side of theconductive substrate, wherein the fourth elevated region comprises afourth planar surface on the first side of the conductive substrate, andwherein fourth elevated region is laterally positioned away from thefootprint of the semiconductor die.
 15. The semiconductor device ofclaim 12, wherein the conductive substrate and the semiconductor die areat least partially encapsulated in a molding material.
 16. Thesemiconductor device of claim 15, wherein the molding material isdisposed between the first elevated region and the second elevatedregion.
 17. The semiconductor device of claim 12, wherein the firstplanar surface of the first elevated region has a first corner that islaterally aligned with a first corner of the first contact pad.
 18. Thesemiconductor device of claim 17, wherein the second planar surface ofthe second elevated region has a second corner that is laterally alignedwith a first corner of the second contact pad.
 19. The semiconductordevice of claim 17, wherein the first planar surface of the firstelevated region has a second corner that is laterally aligned with asecond corner of the first contact pad.
 20. The semiconductor device ofclaim 12, wherein the first planar surface of the first elevated regionhas different dimensions than the second planar surface of the secondelevated region.